1. Field of the Invention
The present invention relates generally to heat exchangers of the type belonging to the group of pipe exchangers designed to exchange heat between a gas and a liquid and, more particularly, to such heat exchangers designed to be used in heat engineering, especially in domestic central heating systems.
2. Description of the Prior Art
Many kinds of pipe heat exchangers are known having different structures depending on their particular environment of use, the fluids circulating in a heat exchange system as well as special demands and needs. A system of pipe elements in which a hot gas or liquid flow is a common feature of pipe heat exchangers, said elements being fastened between two sieve walls and situated in a chamber enclosed in an outer jacket in which heated water or gas circulates. In the case of heat exchangers for domestic central heating systems, in which heat is created by using gas as a fuel, such exchangers are known which are provided with a combustion chamber situated above the upper sieve wall and also having a water inlet as well as a water outlet stub pipes, a gas inlet stub pipe and an exhaust stub pipe. A set of pipe elements is positioned vertically in such exchangers. Heat exchangers are also known for use in the heat power engineering field. Such exchangers are designated as condensers or liquefiers and are built-up of many sets of pipe elements located in a chamber confined with an outer jacket. Pipes of said exchangers are fastened between perforated bottom elements with water chambers situated there between. Such exchangers are used, for example, where water working as an agent for cooling steam provided from outlets of turbines into a chamber closing said pipes is introduced into said pipes. In pipe exchangers of different kinds such as these, and in order to increase the heat exchange efficiency, pipe elements are used of different shapes and inner areas, as well as additional elements of different kinds, such as partitions, additional pipes and the like.
From the Polish patent specification No 1 8 6723 a pipe liquid-to-gas heat exchanger is known in which hot gas is introduced into a chamber closed by an outer jacket, said gas being cooled when flowing around pipes fastened between flat sieve bottoms. A cooling agent flows through these pipes, said agent being delivered and carried out through stub pipes situated in a cover of the sieve bottom. Liquefied gas is drained off an outlet stub pipe situated in an outer jacket surrounding the heat exchange chamber. Additional perforated pipes are also located in this chamber, whereas end parts of said pipes are going through the sieve bottom, and are connected with a collecting pipe which is connected to a vapors off-take pipe. The perforated pipes are used to suck out air from a gas space in the exchanger and to lead it out from the exchanger. Partitions are also located in the exchanger chamber, said partitions being situated crosswise in relation to pipe elements.
From the published international patent application No. WO2008/131616, a heat exchanger is also known comprising an outer cylindrical jacket having inlet and outlet stub pipes with a packet of pipe elements located in said jacket, said pipe elements going through a spiral partition and being connected to sieve walls shaped as flat discs closely forming to the cylindrical outer jacket. These tie rods are from one side fastened in a sieve wall, and their other ends are fastened in the spiral partition. The tie rods are divided into segments provided with distance pipes. Such an exchanger may also be provided with additional pipes going through the spiral partition without being fastened in the sieve walls, upgrading stiffness, protecting against deformations and making it easier to match openings in the spiral partition to the exchanger pipes. The construction of this spiral partition is disclosed in detail and in the cited specification.
From the published international patent application no WO2009/078577 a boiler is known comprising a cylindrical casing, a vertical liquid-gas exchanger, a burner located in a combustion chamber of said exchanger, as well as an inlet and outlet of the water being heated, an exhaust gas outlet, a gas inlet and an instrumentation enabling air supply and making suitable air-gas mixture, and moreover provided with a control device. This embodiment of a heat exchanger has a set of pipe elements rectangular in a section, said pipe elements being regularly distributed inside an outer jacket forming a chamber through which the heated water flows. Upper ends of these pipes are fastened in a flat upper sieve wall, above which there is located a combustion chamber, their lower ends are through a flat lower sieve wall and a combustion gases recycling chamber connected to a combustion gases outlet channel.
Flat partitions, shaped as perforated discs, are located in the water chamber, said pipe elements being run through said discs. These separating partitions improves the heat exchange characteristics because they disturb the water circulation. The partitions are located crosswise to the pipe elements, their diameter is smaller than the inner diameter of the jacket of the exchanger in order to create between the partitions and the jacket slots through which water flows. The partitions are situated crosswise to the pipe elements, their diameter installer than the inner diameter of the jacket of the exchanger so that water flow slots are created. An impact of the width of said slots onto the water circulation and the water pressure acting onto partitions is discussed in the previously cited specification.
The solution described in the previously cited reference proposes to provide said partitions with circulation pipes protecting against a greater water pressure acting onto said partitions, the upper ends of said pipes being fastened in the highest partition, and the lower ends being fastened in the lowest partition. There is also shown an alternative in which walls of the pipe elements are situated in a distance from the edges of openings in those partitions through which they are going, which design makes the water flow disturbances greater, thereby improving the heat exchange efficiency. The described boiler is provided with an additional independent water circuit through spiral pipes disposed in the water chamber around the combustion chamber.
Despite the various advances described in the above prior art references, their continues to exist a need for further improvements in the art of heat exchangers of the type under consideration.